Tse Edmund C M, Varnell Jason A, Hoang Thao T H, Gewirth Andrew A
Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University , Fukuoka 812-8581, Japan.
J Phys Chem Lett. 2016 Sep 15;7(18):3542-7. doi: 10.1021/acs.jpclett.6b01235. Epub 2016 Aug 26.
The development of non-precious-metal (NPM) catalysts to replace the Pt alloys currently used in fuel cells to facilitate the oxygen reduction reaction (ORR) is a vital step in the widespread utilization of fuel cells. Currently, the ORR mechanism for NPM catalysts is not well understood, prohibiting the design and preparation of improved NPM catalysts. We conducted a kinetic isotope effect (KIE) study to identify the rate-determining step (RDS) of this intricate electrocatalytic reaction involving multiple proton-coupled electron transfer (PCET) processes. We observed a KIE of about 2 for the ORR catalyzed by a NPM catalyst, which demonstrates that for these electrocatalysts protons are involved in the RDS during ORR. These results contribute to a more complete understanding of the ORR mechanism and suggest that the design of future NPM catalysts must include careful consideration of the role of protons during ORR.
开发非贵金属（NPM）催化剂以取代目前在燃料电池中使用的铂合金来促进氧还原反应（ORR），是燃料电池广泛应用的关键一步。目前，人们对NPM催化剂的ORR机制了解不足，这阻碍了改进型NPM催化剂的设计与制备。我们进行了动力学同位素效应（KIE）研究，以确定这一涉及多个质子耦合电子转移（PCET）过程的复杂电催化反应的速率决定步骤（RDS）。我们观察到一种NPM催化剂催化的ORR的KIE约为2，这表明对于这些电催化剂，质子在ORR过程中参与了RDS。这些结果有助于更全面地理解ORR机制，并表明未来NPM催化剂的设计必须仔细考虑质子在ORR过程中的作用。
